1. Field of the Invention
This invention relates to a method of testing a charge coupled device (CCD), and more particularly, to a method of testing a CCD in order to detect manufacturing defects in the device.
2. Description of the Prior Art
In two phase CCD's, a common problem is the formation of barriers and pockets at the interface between the storage and transfer regions. These barriers and pockets trap charge and cause transfer inefficiency. The barriers and pockets are formed in the manufacturing process as a result of, for example, misalignment between an implanted region in the CCD and an overlying electrode.
A problem in the prior art has been that there is no method of testing a CCD during the manufacture of the devices to determine either the existence or the size of barriers and pockets in the CCD. Thus, it has been necessary to perform expensive manufacturing steps in order to complete the CCD so that it can be tested. In many cases, the CCD's must be discarded because of defects which should have been detected earlier in the manufacturing process.